Multifunctional composite membrane containing natural antibacterial agent and biomimetic hydrophilic carrier

Abstract

This invention relates to a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier, and pertains to the field of separation membrane manufacturing technology for water treatment applications. The membrane is prepared by blending MCM-41 type honeycomb-structured mesoporous silica modified with tea tree oil (TTO) with a PVDF membrane, aiming to enhance the membrane's antibacterial and antifouling capabilities. TTO, with its excellent antibacterial properties, effectively alleviates biofouling problems, while MCM-41 possesses a high specific surface area and good chemical stability, offering multiple benefits including improved membrane hydrophilicity, reduced fouling, and enhanced essential oil dispersion. The combination of tea tree oil and MCM-41 simultaneously addresses both organic and biofouling issues in PVDF membranes, achieving a synergistic improvement in both material and membrane performance.

Description

Technical Field

[0001] This invention relates to the field of separation membrane manufacturing technology, and more specifically, to a method for preparing and applying a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier. Background Technology

[0002] Membrane separation technology, with its significant advantages of simple operation, low energy consumption, and high separation efficiency, is widely used in water purification fields such as seawater desalination, drinking water purification, and industrial wastewater treatment. Polymer organic molecular membrane materials, represented by polyvinylidene fluoride (PVDF) membranes, have high mechanical strength, strong thermal stability, and strong chemical stability, and have attracted much attention in the field of water purification. Due to the strong hydrophobicity of PVDF itself, flux decline caused by membrane fouling is prone to occur in actual treatment, which seriously affects the membrane separation efficiency. Membrane fouling is mainly divided into organic fouling and biological fouling. Organic fouling mainly includes three categories: proteins, humic acids, and polysaccharides. These pollutants are easily adsorbed and accumulated on the membrane surface, which can easily cause membrane pore blockage and reduce membrane separation efficiency and service life. Biological fouling is divided into three steps: (1) bacteria adsorb onto the separation membrane surface; (2) bacteria grow, reproduce, and secrete exopolymers on the separation membrane; (3) colonies expand and adhere on the membrane, leading to membrane fouling. Therefore, improving the antifouling and antibacterial properties of membranes has become a relevant issue in current membrane technology research.

[0003] Inspired by nature, tea tree oil (TTO), a natural plant essential oil, is considered a highly promising natural antibacterial resource due to its high-efficiency, broad-spectrum antibacterial activity at low concentrations, low likelihood of inducing microbial resistance, and environmentally friendly natural origin. It has demonstrated outstanding performance in various fields such as food and pharmaceuticals. Its main active components are terpenoid antibacterial compounds with relatively small molecular weights (MW=136 ~ 222 Da). Direct addition to PVDF membranes leads to easy volatilization during use, resulting in a short effective time and hindering long-term antibacterial action. To effectively control TTO release, selecting an ideal carrier for TTO immobilization is crucial for sustained release. Typical MCM-41 mesoporous silica, with its honeycomb-shaped ordered pores (pore size 2 ~ 50 nm), high specific surface area, non-toxicity, abundant silanol groups (Si-OH), and good biocompatibility, has become an ideal carrier for loading TTO. Combining TTO with MCM-41 to modify PVDF composite membranes has the functions of improving membrane hydrophilicity, reducing fouling and promoting essential oil dispersion. While improving the membrane's resistance to organic fouling, it also extends the membrane's resistance to biofouling, ultimately achieving the ideal effect of improving membrane separation efficiency and extending service life.

[0004] The purpose of this invention is to provide a composite system containing a natural antibacterial agent and a biomimetic hydrophilic carrier, which is then blended with PVDF to prepare a TTO@MCM-41 / PVDF composite membrane. Using the method described in this invention, a multifunctional composite membrane with both antibacterial and enhanced hydrophilicity can be developed, enabling the treatment of organic pollution while resisting biological pollution. The method provided by this invention offers a novel solution for developing long-lasting antifouling membrane separation materials. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a method for preparing and applying a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier. Compared to unmodified PVDF membranes, the composite membrane prepared by this invention exhibits a higher retention rate for large protein molecules (e.g., bovine serum albumin BSA), improved membrane flux recovery, and a higher sterilization rate against bacteria (e.g., Escherichia coli), and can be widely used in the field of water treatment.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier. The casting solution includes PVDF and a composite material that improves the membrane's antibacterial and antifouling properties. The composite material includes hydrophilic MCM-41 and a natural plant essential oil with sterilization properties; the natural plant essential oil is tea tree oil (TTO).

[0008] This invention also provides a method for preparing a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier, comprising the following steps:

[0009] The template agent and silicon source are mixed and heated for a certain time to obtain a white solution. After crystallization, filtration, washing and drying, a single white powder is obtained. Then, after calcination in a muffle furnace for a period of time, MCM-41 powder is obtained.

[0010] TTO and MCM-41 powders were mixed, and the mixture was subjected to ultrasonic treatment for a certain period of time to obtain a reaction solution. The reaction solution was then aged, washed, dried, and ground to obtain TTO@MCM-41 nanomaterials.

[0011] Polyvinylidene fluoride powder, pore-forming agent and organic solvent are mixed to obtain PVDF casting solution;

[0012] Polyvinylidene fluoride (PVDF) powder, pore-forming agent, organic solvent and TTO@MCM-41 nanomaterials were mixed to obtain TTO@MCM-41 / PVDF casting solution;

[0013] The TTO@MCM-41 / PVDF casting solution was coated onto a nonwoven fabric using the nonsolvent-induced phase separation (NIPS) method, and then immersed and dried in a coagulation bath to obtain an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane containing natural antibacterial agents and a biomimetic hydrophilic carrier.

[0014] Preferably, the template agent is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, etc., and the silicon source is preferably one of tetraethyl orthosilicate, methyl methyl silicate, etc.

[0015] Preferably, the mass ratio of the template agent to the silicon source is 1:5; the heating time is 4-8 h; the crystallization time is 12-24 h; the washing conditions are 30-100 mL of pure water and 30-100 mL of ethanol, washed 2-3 times in sequence; the drying temperature is 40-80 ℃ and the time is 8-24 h; the calcination time is 4-8 h and the calcination temperature is 400-600 ℃.

[0016] Preferably, the mass ratio of TTO to MCM-41 is (1~10):1; the ultrasonic time is 10~30 min, and the ultrasonic temperature is 25 ℃; the washing conditions are 30~100 mL of pure water and 30~100 mL of ethanol, washed 2~3 times in sequence; the drying temperature is 60~80 ℃, and the time is 8~24 h; and the material is passed through a 200~400 mesh sieve after grinding.

[0017] Preferably, the mass ratio of the PVDF powder, pore-forming agent, and organic solvent is 1:(1~3):(8~10); and the concentration of the TTO@MCM-41 / PVDF nanomaterial in the casting solution is 0.1~6.0 g / L.

[0018] Preferably, the pore-forming agent includes at least one of polyvinylpyrrolidone and polyethylene glycol.

[0019] Preferably, the organic solvent includes at least one of dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0020] Preferably, the TTO@MCM-41 / PVDF composite membrane comprises a nonwoven fabric, a PVDF substrate film loaded on the nonwoven fabric, and TTO@MCM-41 nanomaterials loaded on the PVDF substrate film.

[0021] The present invention provides a preparation method for the above-mentioned technical solution to obtain an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier.

[0022] The antibacterial and antifouling composite membrane provided by this invention, containing natural antibacterial agents and a biomimetic hydrophilic carrier, exhibits higher hydrophilicity and significantly improved antifouling performance compared to traditional PVDF membranes. In the TTO@MCM-41 nanocomposite material, TTO possesses extremely strong bactericidal properties, enabling the modified PVDF membrane to exhibit not only strong antifouling performance but also strong antibacterial properties. After modification, the TTO@MCM-41 / PVDF composite membrane achieves a contact angle of 74.44°, a BSA rejection rate of 81.5%, and a flux recovery rate of 92.05%, respectively, with an inhibition rate against Escherichia coli approaching percentage inhibition.

[0023] The method for modifying PVDF composite membranes provided by this invention is simple and easy to implement. All equipment used are conventional instruments in the field. The process cycle is short, the requirements for the process environment are low, and the cost is low. It can be widely used in the preparation of antibacterial and antifouling modified PVDF membranes.

[0024] The method for modifying PVDF composite membranes provided by this invention is a blending modification method. The TTO@MCM-41 in the modified membrane is not easily dissolved with water flow during use, thus avoiding poisoning of water bodies and potential secondary pollution, and ensuring the durability and stability of the membrane structure. Attached Figure Description

[0025] Figure 1 Scanning electron microscope (SEM) image of TTO@MCM-41 nanomaterials prepared for the example;

[0026] Figure 2 FTIR images of MCM-41 and TTO@MCM-41 nanomaterials prepared for the examples;

[0027] Figure 3 The images show the XRD patterns of the MCM-41 and TTO@MCM-41 nanomaterials prepared in the examples.

[0028] Figure 4 The contact angle diagrams are shown for the TTO@MCM-41 / PVDF antibacterial and antifouling composite membrane prepared in the examples and the PVDF membrane prepared in the comparative examples.

[0029] Figure 5 The graph shows the pure water flux and BSA rejection rate of the TTO@MCM-41 / PVDF antibacterial and antifouling composite membrane prepared in the examples and the PVDF membrane prepared in the comparative example.

[0030] Figure 6Flux recovery rate (FRR) of the TTO@MCM-41 / PVDF antibacterial and antifouling composite membrane prepared for the example and the PVDF membrane prepared for the comparative example.

[0031] Figure 7 The reversible fouling rate (Rr), irreversible fouling rate (Rir), and total fouling rate (Rt) of the TTO@MCM-41 / PVDF antibacterial and antifouling composite membrane prepared for the example and the PVDF membrane prepared for the comparative example.

[0032] Figure 8 Antibacterial diagrams of the TTO@MCM-41 / PVDF composite membrane prepared for the example and the PVDF membrane prepared for the comparative example. Detailed Implementation

[0033] This invention provides a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier. The casting solution includes PVDF and a composite material that improves the membrane's antibacterial and antifouling properties. The composite material includes hydrophilic MCM-41 and a natural plant essential oil with sterilization properties; the natural plant essential oil is tea tree oil (TTO).

[0034] This invention also provides a method for preparing a multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier, comprising the following steps:

[0035] The template agent and silicon source are mixed and heated for a certain time to obtain a white solution. After crystallization, filtration, washing and drying, a single white powder is obtained. Then, after calcination in a muffle furnace for a period of time, MCM-41 powder is obtained.

[0036] TTO and MCM-41 powders were mixed, and the mixture was subjected to ultrasonic treatment for a certain period of time to obtain a reaction solution. The reaction solution was then aged, washed, dried, and ground to obtain TTO@MCM-41 nanomaterials.

[0037] Polyvinylidene fluoride powder, pore-forming agent and organic solvent are mixed to obtain PVDF casting solution;

[0038] Polyvinylidene fluoride (PVDF) powder, pore-forming agent, organic solvent and TTO@MCM-41 nanomaterials were mixed to obtain TTO@MCM-41 / PVDF casting solution;

[0039] The TTO@MCM-41 / PVDF casting solution was coated onto a nonwoven fabric using the nonsolvent-induced phase separation (NIPS) method, and then immersed and dried in a coagulation bath to obtain an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane containing natural antibacterial agents and a biomimetic hydrophilic carrier.

[0040] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0041] In this invention, the template agent is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, etc., preferably hexadecyltrimethylammonium bromide; the silicon source is one of tetraethyl orthosilicate, methyl methyl silicate, etc., preferably tetraethyl orthosilicate.

[0042] In this invention, the mass ratio of the template agent to the silicon source is 1:5; the heating time is preferably 4-8 h; the crystallization time is preferably 12-24 h; the washing conditions are preferably 30-100 mL of pure water and 30-100 mL of ethanol, washing 2-3 times in sequence; the drying temperature is preferably 40-80 ℃, more preferably 60-80 ℃, and the drying time is preferably 8-24 h; the calcination time is preferably 4-8 h, and the calcination temperature is preferably 400-600 ℃, more preferably 450-550 ℃.

[0043] In this invention, the mass ratio of TTO to MCM-41 is (1~10):1; the ultrasonic time is preferably 10~30 min, more preferably 15~25 min, and the ultrasonic temperature is preferably 25 ℃; the washing conditions are preferably 30~100 mL of pure water and 30~100 mL of ethanol, washing 2~3 times in sequence; the drying temperature is preferably 40~80 ℃, more preferably 60~80 ℃, and the time is 8~24 h; the material is then passed through a 200~400 mesh sieve after grinding.

[0044] In this invention, the mass ratio of the PVDF powder, pore-forming agent, and organic solvent is 1:(1~3):(8~10); the concentration of the TTO@MCM-41 / PVDF nanomaterial in the casting solution is 0.1~6.0 g / L.

[0045] In this invention, the pore-forming agent includes at least one of polyvinylpyrrolidone and polyethylene glycol, preferably polyethylene glycol.

[0046] Preferably, the organic solvent includes at least one of dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone, with N,N-dimethylacetamide being the most preferred.

[0047] Preferably, the soaking temperature is 25~35 ℃; the soaking time is 6~12 h.

[0048] Preferably, the TTO@MCM-41 / PVDF composite membrane comprises a nonwoven fabric, a PVDF substrate film loaded on the nonwoven fabric, and TTO@MCM-41 nanomaterials loaded on the PVDF substrate film.

[0049] In this invention, the TTO@MCM-41 / PVDF casting solution preferably further includes a degassing treatment before coating. In this invention, the degassing treatment is preferably performed by static degassing; the degassing treatment is preferably carried out in a vacuum drying oven. In this invention, the temperature of the vacuum degassing is preferably 60-80°C, more preferably 70-80°C. In this invention, the time of the degassing treatment is preferably 1-3 hours, more preferably 2 hours.

[0050] In this invention, the nonwoven fabric is preferably a polyester nonwoven fabric, more preferably a polyethylene nonwoven fabric or a polypropylene nonwoven fabric. In this invention, the polyester nonwoven fabric has hydrophilicity, a finer fiber diameter, a larger specific surface area, and a higher porosity.

[0051] In this invention, the mixing of PVDF powder, pore-forming agent, and organic solvent preferably includes adding PVDF powder to a mixed solution of organic solvent and pore-forming agent. The stirring time is preferably 10-24 h, more preferably 16-24 h. In this invention, the stirring is preferably performed with a glass rod. Compared with mechanical stirring, manual glass rod stirring allows for a more complete reaction of the organic solvent and avoids the problem of PVDF powder agglomeration.

[0052] In this invention, the coating is preferably applied by coating; the equipment used for coating is preferably a film scraper. In this invention, the coating thickness is preferably 100-350 μm, more preferably 200-280 μm; the finishing time after coating is preferably 15-50 s, more preferably 20-30 s.

[0053] In this invention, the coagulation bath is preferably a deionized water coagulation bath. The soaking time in the coagulation bath is preferably 10-24 h, more preferably 18-24 h. The temperature of the coagulation bath is preferably 20-30°C, more preferably 25°C.

[0054] In this invention, the drying temperature is preferably 30-60°C, more preferably 40-60°C; the drying time is preferably 5-12 h, more preferably 8-10 h.

[0055] This invention provides an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane prepared by the preparation method described above, containing a natural antibacterial agent and a biomimetic hydrophilic carrier. The membrane comprises a nonwoven fabric and a PVDF membrane attached to the surface of the nonwoven fabric; TTO@MCM-41 nanomaterials are uniformly distributed in the PVDF membrane. In this invention, the antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane has TTO@MCM-41 nanomaterials uniformly distributed on both its surface and interior.

[0056] This invention provides the application of the antibacterial and antifouling TTO@MCM-41 composite membrane containing natural antibacterial agents and biomimetic hydrophilic carriers described in the above technical solution in the field of water treatment, preferably as a separation membrane.

[0057] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0058] Example

[0059] (1) Place 100 mL of deionized water, 70 mL of ammonia solution and 1 g of CTAB into a round-bottom flask and stir magnetically at 250 rpm for 1 hour at 60 °C. After one hour, add 5 g of TEOS dropwise to the solution, stir for 6 hours, and allow to stand for crystallization for 24 hours to obtain MCM-41 suspension;

[0060] (2) The solution obtained in step (1) is filtered and washed using a vacuum filtration device. First, it is washed three times with deionized water, and then three times with anhydrous ethanol.

[0061] (3) The precipitate obtained in step (2) was vacuum dried at 80 °C for 12 h to obtain a preliminary semi-finished product of MCM-41 nanomaterials. Then the semi-finished product was calcined in a muffle furnace at 550 °C for 5 h to obtain MCM-41 nanomaterial powder.

[0062] (4) Weigh 0.5 g of the MCM-41 nanomaterial powder from step (3), and then mix it with 5 mL of TTO to obtain a mixture. React under ultrasonic conditions for 20 min.

[0063] (5) Centrifuge the solution obtained in step (4) several times at a speed of 8000 rpm for 10 min; repeat three times; and shake well with ethanol and deionized water respectively, centrifuge, discard the supernatant, and repeat three times.

[0064] (6) The precipitate obtained in step (5) was vacuum dried at 80 °C for 12 h to obtain TTO@MCM-41 nanomaterials;

[0065] (7) Weigh 0.4 g of TTO@MCM-41 nanomaterial obtained in step (6) and 10 g of PVDF powder, add them to 79.60 mL of DMAc and 10 mL of PEG solvent, mix them evenly, and stir with an artificial glass rod at 80 °C for 24 h to obtain TTO@MCM-41 casting solution.

[0066] (8) The TTO@MCM-41 casting solution was placed in a vacuum drying oven at 60 °C and allowed to stand for 2 h to remove bubbles. After adjusting the coating thickness to 250 μm, it was coated onto a nonwoven fabric and then immersed in a deionized water coagulation bath for 12 h and dried for 8 h to obtain an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane. The TTO@MCM-41 / PVDF composite membrane was cut into 4.2 cm circular pieces for subsequent experiments.

[0067] Comparative Example

[0068] (1) Using the method in step (5) of Example, weigh 10 g of PVDF powder and add it to 79.60 mL of DMAc and 10 mL of PEG solvent and mix evenly, without adding TTO@MCM-41 nanomaterials. Stir with an artificial glass rod at 80 °C for 24 h to obtain PVDF casting solution;

[0069] (2) Using the method in step (6) of the example, the PVDF casting solution was placed in a vacuum drying oven at 60 °C and allowed to stand for 2 h to remove bubbles; after adjusting the film thickness to 250 μm, it was coated onto a non-woven fabric, and then placed in a deionized water coagulation bath for 12 h and dried for 8 h to obtain a PVDF membrane. The PVDF composite membrane was cut into 4.2 cm circular pieces for subsequent experiments.

[0070] Structural characterization and performance testing

[0071] Figure 1 SEM images of MCM-41 and TTO@MCM-41 prepared for the example are shown. The TTO@MCM-41 nanomaterial was photographed by SEM at 100 K magnification. According to the images, it has good morphology and uniform particle size distribution. The morphology is a regular hexagonal mesoporous structure with a relatively smooth surface.

[0072] Figure 2The FTIR spectra of the MCM-41 and TTO@MCM-41 nanomaterials prepared in the examples show that the peaks of the two materials are almost identical, with the appearance of wavelengths corresponding to the stretching and bending vibrations of Si-OH and the Si-O-Si on the SiO2 framework. This indicates that the mesoporous silica material was successfully prepared, and the framework structure of the material was hardly affected after the addition of TTO. The difference is that a wavelength of 1371 cm⁻¹ appears in TTO@MCM-41. −1 The stripe pattern, which is related to the bending vibration of TTO, indicates that the TTO has been successfully loaded.

[0073] Figure 3 The XRD patterns of the MCM-41 and TTO@MCM-41 nanomaterials prepared in the examples show that the MCM-41 nanomaterial exhibits three diffraction peaks at diffraction angles of 2θ of 2.54°, 4.37°, and 5.04°, corresponding to the (100), (110), and (200) crystal planes of hexagonal mesoporous silicon, respectively. This indicates that the sample possesses a highly ordered hexagonal mesoporous structure (a typical characteristic of MCM-41). The lines of TTO@MCM-41 become very flat (almost like a horizontal line) because TTO severely blocks the entrances to the pores, indicating that TTO was successfully loaded onto MCM-41, and the composite material was successfully prepared.

[0074] Test Example 1

[0075] The TTO@MCM-41 / PVDF composite membrane prepared in the examples and the PVDF membrane prepared in the comparative examples were cut into 2 cm × 7 cm pieces, soaked in distilled water for 24 h, and then dried in a 45 ℃ oven for 12 h. They were then adhered to glass slides with double-sided tape, and the contact angle of the membrane surface was measured using a contact angle meter. Pure water was used as the liquid medium for measuring the membrane contact angle under constant room temperature and humidity conditions, with a droplet volume of 10 μL. Three different points were taken for each sample, and the average value was calculated.

[0076] Figure 4 The contact angles of the TTO@MCM-41 / PVDF composite membrane prepared in the examples and the PVDF membrane prepared in the comparative examples are shown. A lower contact angle indicates better hydrophilicity. The contact angle of TTO@MCM-41 / PVDF is smaller than that of PVDF, indicating that the TTO@MCM-41 / PVDF membrane has higher hydrophilicity, which helps reduce the adsorption and accumulation of pollutants on the membrane surface.

[0077] Test Example 2

[0078] The TTO@MCM-41 / PVDF composite membrane prepared in the examples and the PVDF circular membrane prepared in the comparative example were placed in MSC-300 ultrafiltration cups to test the pure water flux and antifouling performance. The membrane to be tested was loaded into the ultrafiltration cup, and pure water was introduced from the upper solution inlet. After ensuring the airtightness of the ultrafiltration cup, the gas cylinder and gas valve were opened, allowing water molecules to pass through the membrane pores under gas pressure. The filtered water flowed out from the lower outlet. The membrane was pre-pressurized at 0.1 MPa for half an hour. The pure water flux (J) was measured first. W1 Then measure the flux of 1 g / L BSA solution (J). P This was used to simulate protein contamination. After cleaning the contaminated membrane, the pure water flux (J) of the cleaned membrane was measured again. W2 ).

[0079] Pure water flux (J) W1 The calculation formula for ) is shown in Equation 1:

[0080] 1

[0081] In Equation 1, J W1 The unit for pure water flux is L m -2 h -1 V1 represents the volume of pure water (L); A1 represents the effective area of ​​the membrane under test (m²). 2 T1 represents the filtering time (h);

[0082] BSA solution flux (J) P The calculation formula is as follows: Figure 2 As shown:

[0083] 2

[0084] In Equation 2, V P Indicates the volume of the BSA solution; A P Indicates the effective area (m²) of the membrane under test. 2 ); T P Indicates the filtering time (h);

[0085] Pure water flux of the cleaning membrane (J) W2 The calculation formula for ) is shown in Equation 3:

[0086] 3

[0087] In Equation 3, V2 represents the volume of pure water; A2 represents the effective area (m²) of the membrane under test. 2 T2 represents the filtering time (h);

[0088] The formula for calculating flux recovery rate (FRR) is shown in Equation 4:

[0089] 4

[0090] The formula for calculating total pollution (Rt) is shown in Equation 5:

[0091] 5

[0092] The formula for calculating reversible pollution (Rr) is shown in Equation 6:

[0093] 6

[0094] The formula for calculating irreversible pollution (Rir) is shown in Equation 7:

[0095] 7

[0096] Figure 5 The graph shows the pure water flux and BSA rejection rate of the TTO@MCM-41 / PVDF composite membrane prepared for the example and the PVDF membrane prepared for the comparative example. The pure water flux of the PVDF membrane is only 31.4 L / m³. 2 h, while the pure water flux of the TTO@MCM-41 / PVDF composite membrane increased to 65.3 L / m 2 h, which is related to Figure 5 The hydrophilicity is also corresponding. Compared with PVDF membrane, the BSA rejection rate of TTO@MCM-41 / PVDF composite membrane increased from 37.0% to 81.5%, indicating that the composite membrane can effectively retain large molecular pollutants and improve the membrane's rejection performance.

[0097] Figure 6 The flux recovery rates of the TTO@MCM-41 / PVDF composite membrane prepared for the example and the PVDF membrane prepared for the comparative example are shown. The PVDF membrane has a FRR of 47.42%, while the FRR of the TTO@MCM-41 / PVDF membrane has increased to 92.05%, which is now close to complete flux recovery.

[0098] Figure 7 The antifouling performance of the TTO@MCM-41 / PVDF composite membrane prepared for the example and the PVDF membrane prepared for the comparative example were compared. The PVDF membrane exhibited severe membrane fouling, with a total fouling rate of nearly 80%, while the TTO@MCM-41 / PVDF membrane showed a reduced total fouling rate. Importantly, it effectively promoted the conversion of pollutants to reversible fouling, reducing the irreversible fouling of the TTO@MCM-41 / PVDF membrane to below 10%. The TTO@MCM-41 / PVDF composite membrane reduced the overall fouling rate and greatly improved the reversibility of fouling. This excellent antifouling performance means that the membrane cleaning frequency can be reduced in actual operation, thereby effectively extending the membrane's service life.

[0099] Test Example 3

[0100] Using Escherichia coli as a bacterial model, a certain concentration of bacterial solution (approximately 10) will be used. 6 (CFU / mL) 100 μL of bacterial suspension was loaded onto the surface of the TTO@MCM-41 / PVDF composite membrane prepared in the example and the PVDF membrane prepared in the comparative example. Then, it was carefully covered with another identical membrane, ensuring that the bacterial suspension would not leak. The sample was then incubated in an incubator at 37°C under normal light conditions. After 2 h of contact, the bacterial cells on the membrane surface were eluted, serially diluted, and counted.

[0101] Figure 8 The colony growth of the TTO@MCM-41 / PVDF composite membrane prepared for the example and the PVDF membrane prepared for the comparative example shows that the TTO@MCM-41 / PVDF composite membrane has excellent antibacterial rate.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier, characterized in that, The casting solution includes PVDF and a composite material containing natural antibacterial agents and a biomimetic hydrophilic carrier. The composite material includes hydrophilic honeycomb-structured mesoporous silica (MCM-41) and natural plant essential oil with bactericidal properties; the natural plant essential oil is tea tree oil (TTO).

2. A multifunctional composite membrane containing a natural antibacterial agent and a biomimetic hydrophilic carrier, characterized in that, The method for preparing the composite material includes the following steps: The template agent is mixed with the silicon source and heated for a certain period of time to obtain a white solution. After crystallization, filtration, washing and drying, a single white powder is obtained, which is then calcined in a muffle furnace for a period of time to obtain MCM-41 powder. TTO and MCM-41 powders were mixed, and the mixture was subjected to ultrasonic treatment for a certain period of time to obtain a reaction solution. The reaction solution was then aged, washed, dried, and ground to obtain TTO@MCM-41 nanomaterials. Polyvinylidene fluoride powder, pore-forming agent and organic solvent are mixed to obtain PVDF casting solution; Polyvinylidene fluoride (PVDF) powder, pore-forming agent, organic solvent and TTO@MCM-41 nanomaterials were mixed to obtain TTO@MCM-41 / PVDF casting solution; The TTO@MCM-41 / PVDF casting solution was coated onto a nonwoven fabric using the nonsolvent-induced phase separation (NIPS) method, and then immersed and dried in a coagulation bath to obtain an antibacterial and antifouling TTO@MCM-41 / PVDF composite membrane containing natural antibacterial agents and a biomimetic hydrophilic carrier.

3. The preparation method according to claim 2, characterized in that, The template agent is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and tetradecyltrimethylammonium bromide, and the silicon source is preferably one of tetraethyl orthosilicate and methyl methyl silicate.

4. The preparation method according to claim 2, characterized in that, The mass ratio of the template agent to the silicon source is 1:5; the heating temperature is preferably 40-80℃; the heating time is preferably 4-8 h; the crystallization time is preferably 12-24 h; the washing conditions are preferably 30-100 mL of pure water and 30-100 mL of ethanol, washing 2-3 times in sequence; the drying temperature is preferably 40-80℃; the drying time is preferably 8-24 h; the calcination time is preferably 4-8 h; and the calcination temperature is preferably 400-600℃.

5. The preparation method according to claim 2, characterized in that, The mass ratio of TTO to MCM-41 is (1~10):1; the ultrasonic time is 10~30 min, and the ultrasonic temperature is 25 ℃; the washing conditions are 30~100 mL of pure water and 30~100 mL of ethanol, washed 2~3 times in sequence; the drying temperature is 60~80 ℃, and the time is 8~24 h; the material is then passed through a 200~400 mesh sieve after grinding.

6. The preparation method according to claim 2, characterized in that, The mass ratio of the PVDF powder, pore-forming agent, and organic solvent is 1:(1 ~ 3):(8 ~ 10); the concentration of the TTO@MCM-41 / PVDF nanomaterial in the casting solution is 0.1 ~ 6.0 g / L.

7. The preparation method according to claim 2, characterized in that, The pore-forming agent includes at least one of polyvinylpyrrolidone and polyethylene glycol.

8. The preparation method according to claim 2, characterized in that, The organic solvent includes at least one of dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

9. The preparation method according to claim 2, characterized in that, The TTO@MCM-41 / PVDF composite film includes a nonwoven fabric, a PVDF base film loaded on the nonwoven fabric, and TTO@MCM-41 loaded on the PVDF base film.

10. The antifouling and antibacterial TTO@MCM-41 / PVDF composite membrane obtained by the preparation method according to claims 1 to 9, characterized in that... It can effectively alleviate membrane organic pollution and biological pollution problems.

Images